This study examines how an intracellular pattern recognition receptor called Nlrp3 contributes to acute kidney injury in a murine model of renal ischemia reperfusion (IR) injury. Experimental renal IR injury mimics ischemic acute kidney injury, a major cause of morbidity and mortality in hospitalized patients. Broad/long-term objectives: The long-term goals of the proposed research are to define how Nlrp3 contributes to injurious tissue responses in the kidney. Specific Aims: The specific objective of this proposal is to test the hypothesis that the cytoplasmic PRR Nlrp3 is a key contributor to the pathogenesis of renal IR injury. Aim 1 will determine whether Nlrp3-mediated signals cause renal tubular epithelial (RTE) cell injury and define the signaling events that lead to this injury. Aim 2 will determine whether Nlrp3-mediated RTE cell injury requires inflammasome formation. Aim 3 will determine whether activation of Nrp3 contributes to renal IR injury primarily through direct (local) or indirect (systemic) mechanisms. Research design and methods for achieving the state goals: The proposed experiments are designed to test for induction of RTE cell apoptosis/necrosis, define the cell death signaling pathways involved in Nlrp3- mediated injury and using a transplant model determine whether systemic mediators of injury are dependent upon Nlrp3 activation. Based on preliminary data, a focus of our studies is on determining whether Nlrp3 signals independently of other inflammasome components, which might identify an entirely new signaling role for Nlrp3 in RTE cells. Health relatedness of project: If the aims of this proposal are met, we will learn how molecules released from injured tissue activate Nlrp3-dependent injurious responses in the kidney. This knowledge is crucial for the development of rational targeted therapies for prevention of ischemic kidney injury in clinical situations where renal hypoxia is anticipated (e.g., pretreatment of donor kidneys prior to harvest for transplantation). We believe that increasing our understanding of the earliest events leading to ischemic kidney injury holds the greatest promise for effective prevention and treatment of this common disorder.